Earth coring apparatus



April 22, 1958 G. S. KUKUCHEK ET AL EARTH CORING APPARATUS Filed May 13,1954 2 Sheets-Sheet 2 lnwm'l'ors: Gmorqc S. Kukuchzk Edwin S. Hzrsegfl-W Their Aqz EARTH CGRING APPARATUS George Stephen Knkuchek, Salt LakeCity, Utah, and Edwin Spalding Hersey, Bakersfield, Calif., assignors toShell Development Company, New York, N. Y., a corporation of DelawareApplication May 13, 1954, Serial No. 429,648

1 Claim. (Cl. 255-72) This invention relates to an apparatus for boringholes in the earth and obtaining cores therefrom which does not requireany circulating medium such as Water or air. It pertains moreparticularly to an apparatus for boring holes to relatively shallowdepths through formations which range from relatively soft andunconsolidated to those which are relatively hard and for obtaining coresamples for stratigraphic control purposes.

In one phase of the exploration operations which are carried on in anattempt to locate oil and gas deposits, there has long been a need for aportable-type drilling and coring apparatus capable of obtaining coresamples for locating lithologic contacts beneath soil covers andWeathered zones as a part of a surface mapping program. Many mechanicalmethods have been used in the past to obtain stratigraphic andlithologic control samples. These methods ranged from shallow core holesdrilled with small rotary drilling equipment to holes drilled bycontinuous coring equipment with diamond drilling tools, both types ofequipment utilizing either air or water as a circulating medium.

The necessary earth samples used as control samples for normal fieldmapping operations may be obtained from sample depths ranging from thesurface down to 50 feet. However, the terrain in many of the areas thatare often studied is extremely rugged and often lacking in any source ofwater supply. Thus, the terrain requires that the sampling equipment bean extremely mobile piece of equipment with versatile drillingcharacteristics. In addition, it is necessary in conventional types ofcoring operations to provide a mobile water tank or air compressor forsupplying the necessary air or water to be circulated in the borehole,which creates considerable practical difficulties.

It is, therefore, a primary object of the present invention to provide aportable and mobile drilling apparatus adapted to travel over roughterrain to obtain core samples beneath an unconsolidated soil cover orweathered layer.

Another object of this invention is to provide a drilling apparatusadapted to penetrate all types of formations, from soft to very hard,down to a depth of 50 feet or more.

A further object of this invention is to provide a drilling apparatusadapted to cut a core sample of at least 1 foot in length after thedrill has penetrated the overburden or weather zone.

A still further object of the present invention is to provide a drillingapparatus adapted to convey cuttings of earth to the surface whiletaking a core without employing a fluid such as air or water for thepurpose.

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coring apparatus employing a core barrel from which soft formation corescan be readily removed without destruction of the core which often takesplace in the present core barrels due to the adhesion of swelling typesof formations to the inner surface of the core barrel.

A still further object of this invention is to provide a coringapparatus adapted to remove borehole cuttings orcoring apparatusillustrated in Figure 1 showing one type It is another object of thisinvention to provide an which normally handicap the mobility of drillingunits.

Still another object of this invention is to provide a of connectingmeans for securing the core barrel to a 1 drill string.

Figure 3 is a longitudinal view in cross-section of one type of a corehead or bit to be used with the coring apparatus of Figure 1.

Figures 4 and 5 illustrate two diiferent types of inner core barrelsadapted to be used with the present coring apparatus.

Figure 6 is a diagrammatical view illustrating the present drilling andcoring apparatus mounted at the rear of a vehicle with the drill stringand coring apparatus positioned in a borehole.

Referring to Figure l of the drawing, the coring device of the presentinvention comprises an elongated tubular body member 11 forming an outercore barrel, there being welded to or integrally formed on the outersurface of said body member 11 a continuous series of external cuttingauger flights 12 extending helically throughout the entire length of thebody member. A suitable coring bit 13 or 13, which may have augerflights 14 secured to its peripheral wall as a continuation of the augerflights 12 on the tubular body member 11, is adapted to be secured tothe lower end of the body member 11.

As shown in Figure 3, the coring bit 13 has an axial bore 15'therethrough to allow a core being cut by said bit to enter the tubularbody member 11 of Figure 1. The bore 15 of the bit 13 has sections ofdifferent shapes and diameters as shown. At 16, the bore is enlarged andis in the form of a hexagonal recess forming one portion of a hexagonalcoupling for securing the coring bit 13 to the tubular member 11. Thehexagonal recess 16 is adapted to receive therein the lower end of thetubular body member 11 which is also cut at 17 in a hexagonal form. Anyother non-circular form of recess may be used whereby the coring bit 13is suitably connected to the body member 11 so that one element .doesnot rotate with relation to the other. The bit 13 may be secured tothebody member 11 in any suitable manner as by means of recessed setscrews 18. l

Another portion 21 of the bore 15 is of a diameter suflicient to receivethe end of an inner core barrel 22 (Figure 5) or the clamping means 23surrounding said inner core barrel 22-. The portion 24 of the. bore 15is tapered to contain a core catcher 25 which may be used, if desired,especially-when drilling through hard formations. The cutting face ofthe bit 13 is provided with a suitable number of teeth 26 which may behardfaced with a tungsten carbide material. Preferably, the bit 13 iscast so that a tapered wear ring 27 is formed at the mouth of the corehead forundercutting a core, i. e., cutting a core of a diameter smallerthan the inner diameter of the inner core barrel 22 (Figure 5); The diameter of the central opening 28 in the face of the coring bit iscritical as this opening must be of a diameter slgihtly smaller than theinner diameter of the split inner core barrel 22, so that the core mayreadily enter the core barrel.

As shown in Figures 1 and 2, a sleeve 30 is secured within the bore ofthe tubular body member 11 in any suitable manner, as by means of apress fit, to form a stop for limiting the movement of the inner corebarrel 22 (Figure when it is inserted into the outer tubular body member11 from the bit end thereof. One or more air holes 32 may be drilledthrough both the wall of the sleeve and the wall of the body member 11to permit the escape of air as a core enters the core barrel duringcoring operations. Secured within and closing the stop sleeve 30 at theend thereof is a male hexagonal shank 33 having one or more keys 34adapted to register with and slide within keyways 35 formed in the stopsleeve 30 to prevent rotation of the shank Within the sleeve. Thehexagonal shank 33 is fixedly held within the sleeve 30 and is securedto the tubular body member 11 by socket set screws 36. The extending endof the hexagonal shank 33 is provided with a spring-loaded latching pin39 adapted to automatically latch into a suitable recess (not shown) inanother section of an auger flight drill string 37, as shown in Figure 6of the drawing, when the male hexagonal shank 33 is inserted into acooperating female hexagonal coupling on the drill string 37.

As stated above, the inner core barrel 22 (Figure 5) is adapted to fitwithin the bore 31 of the body member 11. It has been found in coringoperations that when pressures on certain types of formations arerelieved during the taking of a core, the core extracted from theformation often expands and becomes: wedged within the barrel of thecoring apparatus. In the present coring apparatus, the inner core barrel22, which may be made of stainless steel, is provided with alongitudinal slot in the wall thereof throughout its entire length. Ithas been found that if the inner core barrel is made of a thin fiexiblematerial provided with a longitudinal slot 40, the slot 40 permitsopening the inner core barrel sufficiently to remove a core therefromwith case without destruction of the core. When cores are taken fromhard formations, little swelling of the cores takes place and they maybe readily extracted from the inner core barrel 22. However, when coringformations contain swelling clays, the split inner core barrel 22 isnormally provided with one or more clamps 23 which may be in the form ofshort, rigid tubular sleeve sections which surround the split corebarrel 22 and are mounted thereon before the inner core barrel isinserted into the tubular member 11.

In some cases, the clamp surrounding the split inner core barrel maytake the form of an elongated tubular section 41 (Figure 4), especiallywhen the split inner core barrel is formed of more than one section, forexample, three sections, 42, 43 and 44, as shown in Figure 4. Athree-section split inner core barrel, as shown in Figure 4, may makehandling of some types of cores much simpler, especially when it isdesired to remove soft formation cores which otherwise may jam in theinner core barrel. To facilitate removal of the three split core barrels42, 43 and 44 from the tubular clamp means 41, the-inner surface of thetubular clamp 41 or the outer surfaces of the core barrels 42, 43 and 44may be lubricated in any suitable manner, as by oil or grease. Sincesoft cores stick readily within the split core barrels, it is notnecessary to use a core catcher 25 (Figure 3) in the coring bit forcoring soft formations. If desired, the lower end of the tubularelongated clamp 41 may be provided with a sleeve 45 affixed to theoutside of the clamp. If a core catcher 25 (Figure 3) is used, it maybearagainst the sleeve 45 and the end of tubular clamp 4 1" duringcoring operations. If no sleeve 45 is used,

the core catcher 25 will operate substantially as well by hearingagainst the lower end of the tubular clamp 41.

In operation, while drilling through soft formations, one or moreslotted inner core barrels 42, 43 and 44 (Figure 4) are inserted in thetubular clamp 41 which, in turn, is inserted in the bore 31 of thetubular body member 11 of Figure l. The tubular body member 11 is thenclosed by connecting the coring bit 13 over its lower end by means ofthe recessed set screws 18.

Prior to coring the desired formation with the abovedescribed corebarrel and bit, a borehole 48 (Figure 6) is drilled vertically throughthe unconsolidated material or overburden which covers the formation tobe cored. For drilling shallow holes of from 0 to feet in terrain whichis often rough and lacking in available water for use as a drillingfluid, it has been found that an angertype boring apparatus such asillustrated in Figure 6 of the drawing is most suitable. The mobiledrilling apparatus may be of aconventional type as manufactured byMobile Drilling, Inc., of Indianapolis, Indiana, and may comprise astationary mast 49, about 8 feet high, which is fixedly mounted on therear of a small truck 50. A rotary or turntable 51 is mounted forvertical movement within the mast 49 for rotating an auger-type drillstring 37 connected thereto in either a clockwise or a counterclockwisedirection at speeds at from 10 to 300 R. P. M. A suitable drill bit isconnected to the lower end of the drill string. The turntable 51 ispowered by the truck engine through a power takeoff (not shown).Vertical movement of the turntable 51 is effected by means of ahydraulic cylinder 52 having a 5 foot piston stroke for lifting andlowering the turntable and drill string 37 during coring operations. Ahydraulic pump (not shown), driven by the truck engine, is capable ofsupplying fluid to the cylinder at a maximum pressure of 1500 p. s. i.

After 4 feet of hole has been drilled by the augertype drill string 37,the drill string 37 is disconnected from the turntable 51 and another 4foot section of drill string having auger flights thereon is connectedto the top of the drill string already in the hole and to the turntable.After an other 4 feet of hole has been drilled, another section of drillstring is added. Additional 4 foot sections of anger flight drill stringare added until a hole of a desired depth has been drilled. By use of adrill string having auger flights thereon, cuttings are returned to thesurface without employing a drilling fluid. After the hole has beendrilled it may be cleaned out, if necessary, by any suitable type ofbailer.

With the hole cleaned, the auger flight drill string 37 is again loweredinto the borehole 48. This time, the first or lowermost section of thedrill string 37 having bit 13 attached thereto comprises the tubularbody member 11 (Figure 1) containing the split inner core barrel 22 or aseries of split inner core barrels 42, 43 and 44, as previouslydescribed. When the drill bit has reached the bottom of the borehole,the upper end of the drill string is engaged by the turntable 51 whichis then rotated while being lowered through its 5 foot stroke to cut upto a 4 foot core from the bottom of the borehole. During cuttingoperations, cuttings are being removed to the top of the borehole by theauger flights so that the core obtained is a true representative sampleof the bottom of the borehole and does not comprise compacted cuttingsfrom the bottom of the hole.

After the core has been cut, the entire auger flight drill string isremoved from the borehole 48 and the tubular coring apparatus 11 isdisconnected therefrom. The bit 13 is detached from the end of thetubular body member 11 and the split type core barrel is extracted fromthe bore 31 of said body member. Normally, the split inner core barrelcan be readily removed from the bore of the tubular body member 11, asthe bearing force of the metal inner split core barrel on the metal bodymember 11 is considerably less than that of the dirt-metal frictionalforce obtaining when no inner split core barrel is used. If a clamp 23(Figure 5) or a clamp 41 (Figure 4) surrounds the split inner corebarrel, the clamp 23 or the end of the clamp 41 extends into theenlarged bore section 21 of the bit 13 (Figure 3). Thus, after the bit13 has been removed, the exposed clamp 23 may be grasped by hand or by asuitable wrench and the split core barrel and its clamps pulled from thebore of the tubular body member 11. In extreme cases of sticking of asplit core barrel Within the body member 11, set screws 36 and thehexagonal shank 33 may be removed from the other end of the tubular bodymember 11 so that a rod or other cylindrical body can be inserted intothe bore of the tubular body member 11 from the other end to force thesplit core barrel and its core therefrom.

After the split inner core barrel 22 (Figure 5) has been removed fromthe core of the tubular body member 11 having clamps 23 which are usedto prevent expansion of the split inner core barrel 22 in the bodymember 11, the clamps 23 or the elongated tubular clamp 41 is firstremoved from the split inner core barrel 22. The longitudinal slot 4-0in the inner core barrel 22 is then expanded either by hand or asuitable wedge-shaped tool and the core contained within the inner corebarrel is easily removed by pushing it out one end.

We claim as our invention:

For use with a drilling apparatus having an anger type drill string, acoring apparatus comprising a tubular body member secured to the lowerend of said drill string, spring-loaded coupling means aflixed to theupper end of said tubular body for securing said body to said drillstring, auger flights carried outwardly on said tubular body throughoutits entire length, a core barrel adapted to receive an earth core, saidcore barrel being of thin flexible sheet metal and having a longitudinalslot throughout its entire length, rigid tubular clamp means surroundingsaid slotted core barrel and to prevent radial expansion of said barrelas a core is forced thereinto, said clamp means being of a diameter tofit slidingly within said tubular body member, and a coring bit securedto the lower end of said tubular body member and adjacent the end ofsaid slotted core barrel, said coring bit having an axial openingtherein of a diameter less than the inner diameter of said slotted corebarrel double auger flights being formed on the outer surface of saidbit, and an interior shoulder formed within said hit for seating thecore barrel.

References Cited in the file of this patent UNITED STATES PATENTS548,607 Duggan et a1 Oct. 22, 1895 894,147 Hutchings July 21, 19081,420,242 Christian June 20, 1922 1,577,605 Becker Mar. 23, 19261,785,405 Candee et al Dec. 16, 1930 2,315,590 Cantrell Apr. 6, 19432,334,312 Caldwell Nov. 16, 1943 2,562,841 Compton July 31, 19512,643,858 Hardman June 30, 1953 FOREIGN PATENTS 804.314 Germany Apr. 19,1951

